Method and machine for the manufacture of lengthened objects of concrete



Jan. 21, 1969 P. o. JONEL ET 3,423,492 METHOD AND MACHINE FOR T MAACTURE OF LENGTHENED EC'IS OF CONCRETE Filed I1. 28, 1956 4 I %m)7% 4INVENTORS WW/$6 w/ United States Patent 1,467/65 U.S. Cl. 26470 1m. C1.132% 1/08, 1/14 5 Claims ABSTRACT OF THE DISCLOSURE A method andapparatus for the manufacture of concrete objects by means of a slidingmould, a concrete mixture is fed from a container down on a bed bymoving the container over the bed and forming the concrete mixtur on thebed into a layer having longitudinal borders parallel to each other. Theconcrete mixture in the container has a water-cement number less thanabout 0.32. Water is added to the concrete layer on the bed at the frontend of the layer and the layer is compacted by vibrating the layer aftera stripping of its upper surface by means of a slide having a vibrator.The vibration is carried out so that the water-cement number in theconcrete during the vibration is partly equalized but after thecompleted vibrating operation is somewhat lower in the upper portion ofthe layer than in the lower portion of the same.

According to a known method for moulding concrete elements by means ofhorizontally sliding moulds, such elements being beams, slabs etc. theconcrete is fed out through an opening at the lower end of a containerdown on a plane bed. The container is slowly moved forwards on the bed.In the direction of movement there is after the container arranged aslide provided with a vibrator by means of which the concrete layerformed on the bed is vibrated and compressed. The container and thevibrating slide are moved with an even speed over the bed. The methodrequires that the concrete has a great resistance when it leaves thelayer formed in such 'a' way that the product maintains its shapewithout sagging or bursting. The method further requires that theconcrete has such a consistency and floating ability during thevibration that the iron rods of the reinforcement, when such is used,are completely embedded and enclosed by the concrete. With very thinslabs the vibrator must work in such a way that, simultaneously as theslide is pressed down, it is also given a returning movement. By meansof the last mentioned movement the friction between the slide and theconcrete creates a rearwardly directed force which prevents theoccurring of fissures in the concrete.

When there is a question of manufacturing very thin slabs of concrete,e.g. with a thickness less than about 3 cm., it is diificult at this lowheight to feed the concrete from the container evenly and regularly andto obtain a product without detrimental fissures and cavities (visiblemostly on the surface). So as to fulfil the requirement explained in theaforegoing it is usual to give the concrete a water-cement number, i.e.the weight relationship between the water and the cement in the concretemixture, of more than about 0.33-0.35. At the vibration of such aconcrete the surface will be rich in water and sticky. This means thatthe said friction force in rearwards direction will diminish anddisappear. The result is a formation of fissures in the concrete. Thestickiness of the surface causes the concrete locally to be attached tothe slide and there to obtain a pumping effect which causes the formingof cavities in the surface.

The purpose of the present invention is to eliminate the above drawbacksand to render possible by means of moulding with a sliding mould aproduction of concrete objects with a thickness less than 3 cm. whereasthe product obtained has no detrimental fissures or cavities. Further,the product will have a resistance which has not been possible to attainby means of previously known methods. The main feature of the inventionis to be seen therein that the concrete mixture in the container isgiven a water-cement number that does not exceed about 0.32, prefer-ablyabout 0.25-0.27, and therein that water is continuously added on theconcrete layer fed to the bed at the front end of the same. Due to thefact that the concrete mixture in the container has the low water-cementnumber indicated in the aforegoing, the mixture will, without beingstuck to the container walls, evenly flow out at the lower end of thecontainer in such a way that an even layer is formed on the bed. Due tothe low water-cement number of the mixture the final product will have agreat resistance provided that the compression will be sufficient.

When feeding the concrete out from the container, there will at thefront end of the layer, seen in the direction of movement of the formingmachine, be formed a slope with a certain falling angle and when wateris sprayed against this slope a part of this water will flow down on thebed where it will thus form a small gathering of water. At thesubsequent vibration of the concrete layer this water or at least a partof it will due to the compression be pressed up towards the uppersurface of the layer and there will thus occur an equalizing of thewatercement number throughout the layer. However, the quantity of thewater sprayed onto said slope will not be greater than the compressedconcrete layer under the slide not becoming sticky. It is hereby ensuredthat the final product leaves the forming machine with smooth surfaces,i.e. not only the lower surface turned towards the bed but also theparallel longitudinal borders and the upper surface of the object willbe free of cavities and fissures. The method also makes it possible togive the concrete in the lower portion of the slab a higher and asufficiently great water content in such a way that the reinforcementwhich normally is arranged in this layer will be completely embedded inthe concrete. For the reason that one also obtains a higher watercontent in the upper layer than in the lower one, there is obtained astronger concrete in the upper region which as known is desirable fromthe resistance point of view.

The invention also has reference to a machine for carrying the inventioninto effect.

The invention will now be described with reference to the accompanyingdrawings, showing diagrammatically embodiments of a machine for carryingthe invention into effect. In the drawings:

FIG. 1 shows a vertical longitudinal section through a machine accordingto the invention,

FIG. 2 shows a cross section through the same machine on the line IIIIin FIG. 1, and

FIG. 3 ShOWs a cross section through a machine according to a modifiedembodiment.

The forming machine shown in the drawings comprises a container 1 withan opening 2 extending in the transversal direction of the machine forfeeding out the concrete mixture 3 in the container.

The container 1 is carried on a stand 4 with running wheels 5 for thedisplacement of the machine on a plane bed 6. So as to form the sides ofthe concrete layer or the concrete object 7 manufactured by means of themachine there are arranged parallel side walls 8. The machine is furtherprovided with a slide 9 for forming the upper side 10 of the object 7.The slide 9 is provided with a vibrator 11 for compressing the concretelayer 7 in vertical direction. Reference letter 12 denotes a stripper atthe rear border of the container 1 intended for the smoothening of theupper surface of the concrete mass when it has left the container. Theslide 9 is at its rear end provided with a somewhat resilient steelplate 13 which prevents the concrete layer from forming a transverseelevation, viz. a socalled pressure bank.

The container 1 is frontally provided with a number of spraying jets 14which by means of a hose 15 are in communication with a hose (not shown)for water under pressure. The jets 14 are directed against the frontborder of the feeding opening 2.

The displacement of the machine over the bed 6 in the embodiment shownin FIGS. 1 and 2 is supposed to be carried out by means of a rope orwire 17 attached with one end to the front end of the machine at 16,said wire 17 or the like by means of a winch (not shown) being wheeledup as the towing of the machine proceeds towards this end of the bed.

Reference numeral 18 denotes a number of reinforcing rods which extendin the longitudinal direction of the final concrete object 7.

When the machine by means of the wire 17 is towed in one direction asindicated by means of the arrow 19 in FIG. 1, the rather dry concretemixture (a watercement number of 0.25-0.27) is fed or flows through theopening 2 down onto the bed 6 whereby there is formed the slope 20 ofthe concrete mixture inclining frontwards and somewhat downwards with acertain falling angle below the front border 21 of the opening 2. Ontothis slope there is sprayed water from the jets 14 as evenly aspossible. A part of the water then flows down against the bed 6 wherethus the water-cement number of the layer will be the highest one. Theupper surface of the concrete layer will automatically be smoothened bythe stripper 12. The front border 21 must be situated on a lower levelthan the stripper 12. By means of the slide 9 the concrete layer iscompressed due to the vibrations of the vibrator 11 and thereby thedesired density of the layer is obtained. By means of compression aportion of the water is pressed upwards in such a way that there isobtained a certain equalizing of the water content in the whole of thelayer. However, the water contents at the upper surface will never be sohigh that there occurs any risk that the slide 9 be stuck to the layer.It is hereby ensured a smooth and firm range in the final product alsoat the upper surface. This effect is obtained by means of a correctchoice of the level of the frontal border 21 which may be adjustable invertical direction. The product will be very firm and there is no riskfor its being distorted. The machine may be displaced with a rather highspeed.

When there is a question of manufacturing rather thin concrete objects,there is as a rule no need of vibrating the lateral borders of theobjects. In FIG. 3 there is shown a modification of the machineaccording to FIGS. 1 and 2 provided with lateral walls 8' which, bymeans of springing means 22, are carried on the stand 4 and providedwith a vibrator 11 for the vibration of the walls. It is hereby renderedpossible to compress the concrete layer 7' also in horizontal direction.

In the modification shown in FIG. 3 the machine is supposed to be drivenby means of an electric motor 23 which via a gear device 24 drives therunning wheels 5. In such a case there is no need of any rope or wire17.

By means of tubular cores 25 it is possible continuously to shapelongitudinal holes in the concrete object 7'. The cores 25 are movedcontinuously together with the forming machine over the bed 6.

The machine can be used also for the manufacture of concrete poles forreinforcing the ground.

The invention has been described in the aforegoing for purposes ofillustration only and is not intended to be limited by this descriptionor otherwise except as defined in the appended claims. Other means thanthe jets 14 may be used for the addition of the water in finelydispersed form to the concrete mixture when the latter has left thecontainer 1. It might further be advisable to arrange a feeder screw inthe container 1 or another means for an even feeding of the concretemixture from the container.

What we claim is:

1. A method for the manufacture of lengthened objects, in particularrather thin objects of concrete, by means of a sliding mould, comprisingfeeding a concrete mixture from a container down on a bed bycontinuously moving said container over said bed, forming said concretemixture on said bed into a layer having longitudinal borders parallel toeach other, using a concrete mixture in said container with awater-cement number less than about 0.32, continuously adding water tothe concrete layer on said bed at the front end of said layer,compacting said layer by vibrating the layer after a stripping of itsupper surface by means of a slide having a vibrator, said vibrationbeing carried out so that the water-cement number in the concrete duringthe vibration is partly equalized but after the completed vibratingoperation is somewhat lower in the upper portion of said layer than inthe lower portion of the same.

2. A method as set forth in claim 1 wherein said concrete mixture insaid container has a water-cement number less than about 0.25-0.27.

3. A method as set forth in claim 1 wherein said concrete layer at thefront end forms a slope and said water continuously added flows downalong said slope so that the water-cement number in the concrete in thevicinity of said bed is somewhat higher than at the upper surface ofsaid layer.

4. A machine for the manufacture of lengthened objects of concretecomprising a container for a mixture of concrete having a dischargeopening at the lower end, a stand carrying said container, means fordisplacing said stand along a bed, said stand having side walls forforming the longitudinal sides of a layer of concrete formed on saidbed, a stripper arranged on the rear end of said container forsmoothening the upper surface of said layer, a water spraying devicearranged in front of said container to spray water continuously againstthe front end of said layer, a slide provided with a vibrator andarranged behind said stripper for the vibration of the upper surface ofthe layer formed.

5. A machine as set forth in claim 4 wherein said side walls areprovided with means for vibrating the side portions of said concretelayer.

References Cited UNITED STATES PATENTS 1,814,172 7/1941 Martinet 25-99ROBERT F. WHITE, Primary Examiner.

J. H. SILBAUGH, Assistant Examiner.

us. c1. X.R. 25-32, 41, 103

